| Ambrosia cheiranthifolia | |
|---|---|
Scientific classification  | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Asterids |
| Order: | Asterales |
| Family: | Asteraceae |
| Genus: | Ambrosia |
| Species: | A. cheiranthifolia |
| Binomial name | |
| Ambrosia cheiranthifolia | |
Ambrosia cheiranthifolia is a rare species of flowering plant known by the common names South Texas ambrosia and Rio Grande ragweed. It is native to the coast of South Texas [1] and the Mexican states of Tamaulipas [2] and Coahuila. [3] It occurs in coastal prairie, grassland, and mesquite shrubland habitat. [2] It has declined because its native habitat has been cleared for development, with remaining open savanna invaded by non-native grasses such as buffelgrass (Cenchrus ciliaris). [4] Today there are perhaps 20 populations remaining, but some of these may have very few genetic individuals because the species is clonal, with many cloned plants attached by one rhizome. [5] It is not certain that the plant still exists in Mexico. [6] This is a federally listed endangered species of the United States.
Ambrosia cheiranthifolia is a rhizomatous perennial herb growing erect to a maximum height around 40 centimeters. Several clones usually grow in a dense patch. The stems and herbage are silvery green with a coating of rough gray hairs. The oblong leaves are 3 to 7 centimeters long and oppositely arranged on the lower plant but alternate on the upper stems. The inflorescence contains staminate flower heads in clusters with a few pistillate heads in leaf axils below the clusters. [2]
This plant sometimes occurs alongside slender rush-pea (Hoffmannseggia tenella), another endangered species. [6]
